Cytogenetic studies of 215 new clinical center patients were completed and correlated with diagnostic information. Abnormal karyotypes were frequent in infertility or hypogonadism (28.1%) and idiopathic short stature (11.5%), and increased in premature ovarian failure (3.2%). Abnormalities in short stature usually involved the sex chromosomes (70%). Of 77 Turner syndrome patients, 71.5% were nonmosaic 4 X, and 28.5% had 45,X mosaicism or a structurally abnormal X. All 19 new patients with mental disorders were fragile-X negative; one carried a familial autosomal rearrangement which will be further investigated. Our ovarian failure results were submitted for publication, together with data from a clinical trial of gonadotropin suppression treatment. Findings in familial parathyroid carcinoma cell cultures were also submitted for publication; clones with an autosomal translocation, chromosome 7 aneuploidy, and chromosome 9 inversion were identified in the tumor. CNS studies of young adult fragile X patients are being reported and include our determination of fragile-X expression levels. Completed studies of mosaic trisomy 21 in a non-mentally retarded adult with presenile dementia and a family with carotid body tumor with pheochromocytoma were published. We plan to continue these patients investigations. Our goal will be to correlate cytogenetic findings with molecular analyses and clinical status. Variations of the sex chromosomes will be emphasized.